Question: Last Monday, Luis's parents gave birth to twins and named them Omar and Tiffany. When they were first born, Omar weighed 7.05 pounds and was 21.5 inches tall, and Tiffany weighed 8.69 pounds. How much did the babies weigh in total?
Explanation: To find the weights of the 2 babies, we need to add their weights together. Omar's weight + Tiffany's weight = total weight. ${7}$ ${0}$ ${5}$ ${8}$ ${6}$ ${9}$ ${+\vphantom{0}}$ ${4}$ ${7}$ ${5}$ ${1}$ Together, the babies weigh 15.74 pounds.